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Re: [PATCH v3 3/5] virtio-pci: add support for configure interrupt


From: Jason Wang
Subject: Re: [PATCH v3 3/5] virtio-pci: add support for configure interrupt
Date: Wed, 27 Jan 2021 13:44:36 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0


On 2021/1/26 下午3:42, Cindy Lu wrote:
Add support for configure interrupt, use kvm_irqfd_assign and set the
gsi to kernel. When the configure notifier was eventfd_signal by host
kernel, this will finally inject an msix interrupt to guest

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
  hw/virtio/virtio-pci.c | 92 ++++++++++++++++++++++++++++++++++--------
  1 file changed, 75 insertions(+), 17 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 36524a5728..8e192600b8 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -664,7 +664,6 @@ static uint32_t virtio_read_config(PCIDevice *pci_dev,
  }
static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy,
-                                        unsigned int queue_no,
                                          unsigned int vector)
  {
      VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
@@ -691,23 +690,17 @@ static void 
kvm_virtio_pci_vq_vector_release(VirtIOPCIProxy *proxy,
  }
static int kvm_virtio_pci_irqfd_use(VirtIOPCIProxy *proxy,
-                                 unsigned int queue_no,
+                                 EventNotifier *n,
                                   unsigned int vector)
  {
      VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
-    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
-    VirtQueue *vq = virtio_get_queue(vdev, queue_no);
-    EventNotifier *n = virtio_queue_get_guest_notifier(vq);
      return kvm_irqchip_add_irqfd_notifier_gsi(kvm_state, n, NULL, 
irqfd->virq);
  }
static void kvm_virtio_pci_irqfd_release(VirtIOPCIProxy *proxy,
-                                      unsigned int queue_no,
+                                      EventNotifier *n ,
                                        unsigned int vector)
  {
-    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
-    VirtQueue *vq = virtio_get_queue(vdev, queue_no);
-    EventNotifier *n = virtio_queue_get_guest_notifier(vq);
      VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
      int ret;
@@ -722,7 +715,8 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
      VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
      unsigned int vector;
      int ret, queue_no;
-
+    VirtQueue *vq;
+    EventNotifier *n;


new line is needed.


      for (queue_no = 0; queue_no < nvqs; queue_no++) {
          if (!virtio_queue_get_num(vdev, queue_no)) {
              break;
@@ -731,7 +725,7 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, 
int nvqs)
          if (vector >= msix_nr_vectors_allocated(dev)) {
              continue;
          }
-        ret = kvm_virtio_pci_vq_vector_use(proxy, queue_no, vector);
+        ret = kvm_virtio_pci_vq_vector_use(proxy,  vector);
          if (ret < 0) {
              goto undo;
          }
@@ -739,7 +733,9 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, 
int nvqs)
           * Otherwise, delay until unmasked in the frontend.
           */
          if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
-            ret = kvm_virtio_pci_irqfd_use(proxy, queue_no, vector);
+            vq = virtio_get_queue(vdev, queue_no);
+            n = virtio_queue_get_guest_notifier(vq);
+            ret = kvm_virtio_pci_irqfd_use(proxy, n, vector);
              if (ret < 0) {
                  kvm_virtio_pci_vq_vector_release(proxy, vector);
                  goto undo;
@@ -755,13 +751,69 @@ undo:
              continue;
          }
          if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
-            kvm_virtio_pci_irqfd_release(proxy, queue_no, vector);
+            vq = virtio_get_queue(vdev, queue_no);
+            n = virtio_queue_get_guest_notifier(vq);
+            kvm_virtio_pci_irqfd_release(proxy, n, vector);
          }
          kvm_virtio_pci_vq_vector_release(proxy, vector);
      }
      return ret;
  }
+static int kvm_virtio_pci_vector_config_use(VirtIOPCIProxy *proxy)
+{
+
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+    unsigned int vector;
+    int ret;
+    EventNotifier *n = virtio_get_config_notifier(vdev);
+
+    vector = vdev->config_vector ;
+    ret = kvm_virtio_pci_vq_vector_use(proxy, vector);
+    if (ret < 0) {
+        goto undo;
+    }
+    ret = kvm_virtio_pci_irqfd_use(proxy,  n, vector);
+    if (ret < 0) {
+        goto undo;
+    }
+    return 0;
+undo:
+    kvm_virtio_pci_irqfd_release(proxy, n, vector);
+    return ret;
+}


newline is needed.


+static void kvm_virtio_pci_vector_config_release(VirtIOPCIProxy *proxy)
+{
+    PCIDevice *dev = &proxy->pci_dev;
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+    unsigned int vector;
+    EventNotifier *n = virtio_get_config_notifier(vdev);
+    vector = vdev->config_vector ;
+    if (vector >= msix_nr_vectors_allocated(dev)) {
+        return;
+    }
+    kvm_virtio_pci_irqfd_release(proxy, n, vector);
+    kvm_virtio_pci_vq_vector_release(proxy, vector);
+}
+
+static int virtio_pci_set_config_notifier(DeviceState *d,  bool assign)
+{
+    VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+    EventNotifier *notifier = virtio_get_config_notifier(vdev);
+    int r = 0;
+    if (assign) {
+        r = event_notifier_init(notifier, 0);
+        virtio_set_config_notifier_fd_handler(vdev, true, true);
+        kvm_virtio_pci_vector_config_use(proxy);
+    } else {
+        virtio_set_config_notifier_fd_handler(vdev, false, true);
+        kvm_virtio_pci_vector_config_release(proxy);
+        event_notifier_cleanup(notifier);
+    }
+    return r;
+}


Two questions, don't we need to check whether or not MSIX is enalbed in this case? Instead of introducing new helpers that is easy to be buggy I still prefer to re-use virtio_pci_set_guest_notifier:

We can switch to use accepts EventNotifier instead of virtqueue index. And we need also convert virtqueue_set_guest_notifier_fd_handler() to accept EventNotifier.


+
  static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
  {
      PCIDevice *dev = &proxy->pci_dev;
@@ -769,7 +821,8 @@ static void kvm_virtio_pci_vector_release(VirtIOPCIProxy 
*proxy, int nvqs)
      unsigned int vector;
      int queue_no;
      VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
-
+    VirtQueue *vq;
+    EventNotifier *n;


newline is needed.

Thanks


      for (queue_no = 0; queue_no < nvqs; queue_no++) {
          if (!virtio_queue_get_num(vdev, queue_no)) {
              break;
@@ -782,7 +835,9 @@ static void kvm_virtio_pci_vector_release(VirtIOPCIProxy 
*proxy, int nvqs)
           * Otherwise, it was cleaned when masked in the frontend.
           */
          if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
-            kvm_virtio_pci_irqfd_release(proxy, queue_no, vector);
+            vq = virtio_get_queue(vdev, queue_no);
+            n = virtio_queue_get_guest_notifier(vq);
+            kvm_virtio_pci_irqfd_release(proxy, n, vector);
          }
          kvm_virtio_pci_vq_vector_release(proxy, vector);
      }
@@ -823,7 +878,7 @@ static int virtio_pci_vq_vector_unmask(VirtIOPCIProxy 
*proxy,
              event_notifier_set(n);
          }
      } else {
-        ret = kvm_virtio_pci_irqfd_use(proxy, queue_no, vector);
+        ret = kvm_virtio_pci_irqfd_use(proxy, n, vector);
      }
      return ret;
  }
@@ -835,13 +890,15 @@ static void virtio_pci_vq_vector_mask(VirtIOPCIProxy 
*proxy,
      VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
      VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
+ VirtQueue *vq = virtio_get_queue(vdev, queue_no);
+    EventNotifier *n = virtio_queue_get_guest_notifier(vq);
      /* If guest supports masking, keep irqfd but mask it.
       * Otherwise, clean it up now.
       */
      if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
          k->guest_notifier_mask(vdev, queue_no, true);
      } else {
-        kvm_virtio_pci_irqfd_release(proxy, queue_no, vector);
+        kvm_virtio_pci_irqfd_release(proxy, n, vector);
      }
  }
@@ -2137,6 +2194,7 @@ static void virtio_pci_bus_class_init(ObjectClass *klass, void *data)
      k->ioeventfd_assign = virtio_pci_ioeventfd_assign;
      k->get_dma_as = virtio_pci_get_dma_as;
      k->queue_enabled = virtio_pci_queue_enabled;
+    k->set_config_notifiers = virtio_pci_set_config_notifier;
  }
static const TypeInfo virtio_pci_bus_info = {




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